Recaptcha blocking IPs?

Has anyone ever had their IP blocked by recaptcha? I've never seen this happen before, but I use private proxies to post to various web 2.0 sites, and the other day I realized that when using some (some, not all) of my private proxies the recaptcha image wasn't being displayed on the web 2.0 registration form anymore. I then went to http://www.google.com/recaptcha/learnmore to see if the recaptcha form would display, and it did not. The following message is displayed: "We're sorry... ... but your computer or network may be sending automated queries. To protect our users, we can't process your request right now."

The only thing I have used these private proxies for is scraping Google. I thought maybe my IP was blocked because of scraping, but that would only be a temporary ban. I suppose the person that used the IPs before me could have got them banned.

I also waited 48 hours but the ban is still in place. I plan to request that my proxy IPs are replaced, but I'd like to know if anyone else has experienced this and if so what you think may have caused it, I would like to avoid this in the future if possible.

That's quite common, since Recaptcha is run by Google. It just means you have been scraping too hard. I would recommend that you get a LOT more proxies for serp scraping, or start harvesting open proxies to use instead, and keep your private proxies for doing limited stuff like signing up for new accounts.